This is exactly my train of thought. Viewing him as a rule follower, fraternization should be a big no no. But then, maybe he has finally chilled out a little on that. Maybe it's end of the world. Maybe it's maturity. Maybe it's how totally freaking extra awesome our Inquisitor is.
So, I guess I would hope it's addressed... but then, given the limited romance word budget, I'd rather them spend words on other aspects of our relationship.
To be fair, the situation with Amell/Surana was so much different, that sleeping with the Reverence doesn't even seem like a problem in comparison.
With f!Mage it was absolutely forbidden. Plus, if Cullen had allowed himself to enjoy her company, and it had been discovered, her punishment would have been much worse than his, and I'm sure he knew it. And that would be the violation of his vows, because instead of protecting the mage, he would have done the opposite. Besides, he was a young templar back then, probably with no rich parents to bribe anyone for him, so his career depended solely on his actions, and I believe he was afraid to risk his future. He was crushing on her, but he still had enough common sense to restrict that to just talking.
With Inquisitor it will be different. They don't have that huge Chantry machine looming over them, so who will punish them? And they are equals, more or less. I don't really see any obstacles. Subordination is such a minor thing when you are facing the end of the world. I won't be surprised if BioWare won't see an issue here as well.